title: Perfusion of the juxtapapillary retina and optic nerve head in acute ocular hypertension.
abstract: Chronically elevated intraocular pressure (IOP) is often associated with glaucomatous optic nerve atrophy. Impaired blood flow may play a role in the pathogenesis of this disease. We present data concerning juxtapapillary retinal and optic nerve-head blood flow during acute increases in IOP. With the combination of a laser Doppler flowmeter and a scanning-laser system (Scanning Laser Doppler Flowmeter, SLDF; Heidelberg Engineering) the perfusion of the retina and the optic nerve head was quantified and visualized. Juxtapapillary retinal and optic nerve-head blood flow was measured simultaneously by SLDF during variations in IOP induced by a suction cup in nine healthy volunteers. The ocular pressure was increased for 2 min to IOP +15 mmHg, then to IOP +30 mmHg, and finally, to IOP +45 mmHg. Ocular perfusion pressure (PP) was calculated as the mean arterial blood pressure minus the IOP. The declines in juxtapapillary retinal flow as expressed in present per 10-mmHg IOP elevation ranged from 3.6% to 14.1% (median 7.4%). Over all measurements we found a significant linear relationship between juxtapapillary retinal blood flow and PP (r = 0.55, P < 0.0001). The observed decrease in optic nerve-head blood flow with increasing IOP was significantly greater as compared with the retinal blood flow decrease (8.4%/10 mmHg versus 7.4%/10 mmHg, P < 0.05). SLDF enables the quantification and visualization of perfused capillaries of the retina and the optic nerve head in high resolution. Acute elevations of IOP led to a decreases in juxtapapillary retinal and optic nerve-head blood flow of 7.4% and 8.4%/ 10-mmHg IOP increase, respectively.
authors.affiliation: Department of Ophthalmology, University of Erlangen-Nürnberg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Michelson
authors.forename: M J
authors.initials: MJ
authors.lastname: Groh
authors.forename: M
authors.initials: M
authors.lastname: Langhans
mesh_terms: D000208:Acute Disease; D001783:Blood Flow Velocity; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D009798:Ocular Hypertension / Q000503:physiopathology*; D009887:Ophthalmoscopy; D009898:Optic Disk / Q000098:blood supply*; D010477:Perfusion; D012039:Regional Blood Flow / Q000502:physiology; D012171:Retinal Vessels / Q000502:physiology*